Different literatures on estimating higher heating values of fuels
using proximate analysis were analyzed and the possible new correlations
based on non-volatile, volatile, and non-organic ratios
were proposed (Table 2). The correlations were initially established
by considering various linear effects to simplify such correlations.
The constant terms of proposed correlations were determined by
using the Microsoft Excel Solver Tool with the help of 250 different
published data of proximate analysis and higher heating values by
dry weight basis (Table 3). The main principle behind the determination
of constant terms is to minimize the sum of square errors
between estimated and actual values of higher heating values.
The goodness of the correlations was determined by analyzing different
form of estimating errors which is described in Section 2.1.
The best correlation is the one with the least error values among
the all proposed correlations.
Based on the extent of effect of different ratios of proximate
data on heating values, the selected correlation is further analyzed
for its non-linear effects to reduce the error level. The developed
correlations were validated by using 10 experimentally determined
higher heating value and proximate values and then compared
with published correlations. The experimental data were
obtained from biomass samples at AIT which were collected for
two different months. The tests were carried out at AIT Energy laboratory
with the help of Bomb Calorimeter under the British Standard
(BS 4379) and proximate analysis under the American
Standard of Testing Materials.